Which of the following is a common sign of a degraded wheel bearing?

A common sign of a degraded wheel bearing is excessive heat and noise during operation. When a wheel bearing begins to fail, it generates increased friction due to wear and tear, which results in higher operational temperatures. Additionally, a failing bearing often produces unusual sounds, such as grinding or rumbling, which are indicative of the internal components not functioning smoothly anymore.

This phenomenon is critical for maintaining safety and performance in rail operations; recognizing it early can prevent further damage to the wheel assembly or even catastrophic failures. Monitoring for these symptoms allows for timely maintenance interventions, helping to ensure both the efficiency and safety of the rail system.

While other options might indicate issues within the railway infrastructure or components, they do not directly correlate with the failure of the wheel bearing like excessive heat and noise do. For example, rust accumulation may affect components but is not a direct sign of bearing degradation. Frequent derailments can signal a range of mechanical issues, and improper alignment of rail tracks typically results from structural issues rather than bearing performance.